This is a great product. But it's not meant to replace Excel entirely. It would be foolish of Apple to undermine its largest developer, Microsoft. But it does raise the bar on spreadsheet design.

I started my spreadsheet life with Visicalc long ago, analyzing the Federal Budget. Numbers '08 imported my long developed business models without problem - well almost. Numbers cannot import linked spreadsheets. But regardless, my models are less than 600 rows long, and I will be using Numbers for future spreadsheet development. And the superb integration with Keynote and Pages makes iWork a real pleasure for all but the most esoteric tasks.

AND, each iWork package, including Numbers is thoroughly documented by individual 250+ page .pdf manuals available for download from Apple (not the documents in the iWorks retail package).